问题描述
Flutter：第一次在第二页上，传入的参数值为null。如果我进行热装，则此值不为空。
也许是因为TabBar，但是您如何在使用TabBar时第一次获得实际价值？
第一页。而且idBou在这里不为空
class BoutiquePage extends StatefulWidget {
int idboutique;
BoutiquePage({this.idboutique});
@override
_BoutiquePageState createState() => _BoutiquePageState();
}
class _BoutiquePageState extends State<BoutiquePage> {
SharedPreferences sharedPreferences;
final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
String idBou ;
String nomAbon ;
String prenomAbon ;
String telAbon ;
String addAbon;
String nomBou;
String ville;
String pays;
String lien_photo_bout;
bool _isLoading = false;
String _errorText;
get article_afficher333 => article_afficher333;
@override
void initState() {
setState((){
getShaerInstance();
});
super.initState();
}
getShaerInstance() async {
sharedPreferences = await SharedPreferences.getInstance();
}
Future<Map<String,dynamic>> getAllStoreInfoData2(int idboutique) async {
final response = await http.get(http://xxxxxx.com+"boutique/home?id_bout="+idboutique.toString());
if (response.statusCode == 200) {
final jsonResponse = json.decode(response.body);
BoutiqueData myData = new BoutiqueData.fromJson(jsonResponse);
Map<String,dynamic> boutiqueinfodata = Map();
boutiqueinfodata["boutiqueType"] = myData.v_boutique.typeBoutique;
return boutiqueinfodata;
} else {
throw Exception("Failed to load Data");
}
}
//SharedPreferences
@override
Widget build(BuildContext context) {
Widget myboutiqueinfodata = FutureBuilder(
future: getAllStoreInfoData2(widget.idboutique),builder: (context,snapshot) {
if (snapshot.hasData) {
Map<String,dynamic> alldata = snapshot.data;
typeBoutique = alldata["boutiqueType"];
List<ListeInfoBoutique> boutiqueInfoData = alldata["boutiqueInfoData"];
for (var i = 0; i < boutiqueInfoData.length; i++) {
idBou = boutiqueInfoData[i].idBou;
nomAbon = boutiqueInfoData[i].nomAbon;
prenomAbon = boutiqueInfoData[i].prenomAbon;
telAbon = boutiqueInfoData[i].telAbon;
addAbon = boutiqueInfoData[i].addAbon;
}
return Scaffold(
body: ListView(
children: <Widget>[
],),);
}else if (snapshot.hasError) {
return Container(
child: Center(
child: Text(AppLocalizations.of(context)
.translate('_MSG_ER_CONNEXION_CHARGE_DATA'),style: TextStyle(
fontSize: 18,fontFamily: 'Questrial'
),);
}
return new Center(
child: CircularProgressIndicator(),);
});
return DefaultTabController(
length: 5,child: Scaffold(
key: _scaffoldKey,appBar: AppBar(
title: Text(AppLocalizations.of(context)
.translate('_MY_STORE'),style: TextStyle(color: Colors.white,fontFamily: "Questrial"),iconTheme: new IconThemeData(color: Color(0xFFFFFFFF)),actions: <Widget>[
//
],bottom: TabBar(
isScrollable: true,indicatorColor: Colors.white,indicatorWeight: 5.0,//onTap: (){},tabs: <Widget>[
Tab(
child: Container(
child: Text(AppLocalizations.of(context)
.translate('_STORE_INFO'),fontSize: 18.0,fontFamily: 'Questrial'),Tab(
child: Container(
child: Text(AppLocalizations.of(context)
.translate('_MY_ARTICLES'),],body: TabBarView(
children: <Widget>[
myboutiqueinfodata,MesArticles(idboutique: idBou),);
}
}
首次打印为null且热重新加载后为null的密码页不为空
class MesArticles extends StatefulWidget {
final String idboutique;
const MesArticles({Key key,this.idboutique}) : super(key: key);
@override
_MesArticleState createState() => _MesArticleState();
}
class _MesArticleState extends State<MesArticles> {
@override
Widget build(BuildContext context) {
print(widget.idboutique.toString()); // it print null for fist time. After hot reload it become not null
return Scaffold(
body: Text(widget.idboutique.toString()),//<== it print null for fist time.
);
}
}
解决方法
尝试此代码。我认为Future builder是抛出null的原因。
class BoutiquePage extends StatefulWidget {
int idboutique;
BoutiquePage({this.idboutique});
@override
_BoutiquePageState createState() => _BoutiquePageState();
}
class _BoutiquePageState extends State<BoutiquePage> {
SharedPreferences sharedPreferences;
final GlobalKey<ScaffoldState> _scaffoldKey = new GlobalKey<ScaffoldState>();
String idBou ;
String nomAbon ;
String prenomAbon ;
String telAbon ;
String addAbon;
String nomBou;
String ville;
String pays;
String lien_photo_bout;
bool _isLoading = false;
bool _isLoaded = false;
bool _isError = false;
String _errorText;
get article_afficher333 => article_afficher333;
@override
void initState() {
setState((){
getShaerInstance();
});
super.initState();
}
getShaerInstance() async {
sharedPreferences = await SharedPreferences.getInstance();
}
Future<Map<String,dynamic>> getAllStoreInfoData2(int idboutique) async {
final response = await http.get("http://xxxxxx.com/" + "boutique/home?id_bout="+idboutique.toString());
if (response.statusCode == 200) {
final jsonResponse = json.decode(response.body);
BoutiqueData myData = new BoutiqueData.fromJson(jsonResponse);
Map<String,dynamic> boutiqueinfodata = Map();
boutiqueinfodata["boutiqueType"] = myData.v_boutique.typeBoutique;
return boutiqueinfodata;
} else {
throw Exception("Failed to load Data");
}
}
//SharedPreferences
initDataFromServer(idboutique) async {
try {
var alldata = await getAllStoreInfoData2(idboutique);
var typeBoutique = alldata["boutiqueType"];
List<ListeInfoBoutique> boutiqueInfoData = alldata["boutiqueInfoData"];
for (var i = 0; i < boutiqueInfoData.length; i++) {
idBou = boutiqueInfoData[i].idBou;
nomAbon = boutiqueInfoData[i].nomAbon;
prenomAbon = boutiqueInfoData[i].prenomAbon;
telAbon = boutiqueInfoData[i].telAbon;
addAbon = boutiqueInfoData[i].addAbon;
}
setState(() {
_isLoaded = true;
_isLoading = false;
_isError = false;
});
} catch (e) {
print(e);
setState(() {
_isLoaded = true;
_isLoading = true;
_isError = true;
});
}
}
@override
Widget build(BuildContext context) {
if (_isLoaded == false && _isLoading == false) {
_isLoading = true;
initDataFromServer(widget.idboutique);
}
return DefaultTabController(
length: 5,child: Scaffold(
key: _scaffoldKey,appBar: AppBar(
title: Text(AppLocalizations.of(context)
.translate('_MY_STORE'),style: TextStyle(color: Colors.white,fontFamily: "Questrial"),),iconTheme: new IconThemeData(color: Color(0xFFFFFFFF)),actions: <Widget>[
//
],bottom: TabBar(
isScrollable: true,indicatorColor: Colors.white,indicatorWeight: 5.0,//onTap: (){},tabs: <Widget>[
Tab(
child: Container(
child: Text(AppLocalizations.of(context)
.translate('_STORE_INFO'),fontSize: 18.0,fontFamily: 'Questrial'),Tab(
child: Container(
child: Text(AppLocalizations.of(context)
.translate('_MY_ARTICLES'),],body: TabBarView(
children: <Widget>[
_isLoaded == false ? Center(
child: CircularProgressIndicator(),): (_isError == false ? Text("Your data Loaded") : Text("Error")),_isLoaded == false ? Center(
child: CircularProgressIndicator(),): (_isError == false ? MesArticles(idboutique: idboutique) : Text("Error")),);
}
}
class MesArticles extends StatefulWidget {
final String idboutique;
const MesArticles({Key key,this.idboutique}) : super(key: key);
@override
_MesArticleState createState() => _MesArticleState(idboutique: idboutique);
}
class _MesArticleState extends State<MesArticles> {
final String idboutique;
_MesArticleState({this.idboutique});
@override
Widget build(BuildContext context) {
print(widget.idboutique.toString()); // it print null for fist time. After hot reload it become not null
return Scaffold(
body: Text(widget.idboutique.toString()),);
}
}